Genus: Abyssosaurus BEREZIN, 2011
Etymology: Greek, abyssos, "bottom-less" and Latin, saurus, "lizard."

Species: nataliae BEREZIN, 2011
Etymology: In honor of Nataliya Berezina, research worker, my (A. Yu. Berezin) associate and wife.

Holotype: MChEIO, no. PM/1

Locality: Left tributary of the Saura River, Menya River, 55°02'43.6"N, 46°09'46.2"E, Poretskii District, Chuvashia Republic, European Russia.

Horizon:

Biostratigraphy: Speetoniceras veriscolor Zone.

Age: Upper Hauterivian Stage, Upper Neocomian Subepoch, Middle Early Cretaceous Epoch, Early Early Cretaceous.

Material: Left side of the skull are the premaxillae, anterior, middle, posterior parts of the maxillae, jugle, and cosely adjoining parts of the ectopterygoid and pterygoid, part of the frontal, postfrontal, postorbital, parietal, lower part of the squamosal, exoccipital-opisthocicum and quadrate, anterior presymphyseal and and dentary fragments, and the posterior part of the dental, supraangul, angual, articular and probably fragments of some other bones, the right side partial supraoccipital, prooticum, partial asioccipital-basisphenoideum. The axial skeleton is represented by vertebrae of all regions and pectoral ribs. In the cervical region, 44 vertebrae of presumable 51 are preserved, 7 vertebrae (between C15 and C23) are absent.

Note: Skull material described by Berezin 2018.